Amazon has already conquered online retail, but it still takes too long to get your groceries. Why shouldn't they be at your door in an hour?

That's the problem that Instacart, a new startup coming out of prestigious startup school Y Combinator, wants to solve. It's not the only startup attacking same-day delivery, considered a "holy grail" in technology, but it's one that certainly shows an enormous amount of promise.

Instacart charges a flat fee to deliver groceries to your home in just an hour (or three). Its salespeople are equipped with the best tech and apps to get your groceries to your door immediately.

Here's how it works: you fire up the app, select some groceries to buy, and an hour later they arrive at your door. You pay a delivery fee that's about $15.

It might seem steep, but there's certainly a ton of demand for it: the app has already delivered tens of thousands of items.

It's not the first startup to do online grocery shopping, though. Webvan was a famous dotcom-era startup that did much the same thing, now owned by Amazon.

We caught up with co-founder Apoorva Mehta to find out where he plans to take Instacart. Here's what we learned:

After being operational for just a few weeks, Instacart has delivered tens of thousands of items. That's pretty impressive growth for an app that just came out of Y Combinator, even for one of the top startups in the incubator.

Instacart might expand to other verticals, but it's just groceries for now. Amazon started with just books, and now it's the top retail site on the web. Instacart just wants to do groceries right first before expanding into new verticals.

Here's a lightly edited transcript of the interview:

BUSINESS INSIDER: Can you tell me a little bit about your background?

APOORVA MEHTA: I used to be at Amazon.com, I was working on supply chain, a lot of what we are doing at Instacart is inspired by my work at Amazon. We fulfill items from local stores. A lot of the routing algorithms we're building was inspired heavily from my work at Amazon. Amazon is like clockwork, it has taken some time to get there and become a well-oiled machine and it's great to have that experience to start off with at Instacart.

I was at Amazon for 2.5 years, and this problem was there for me all the time. You would realize that you would shop for everything, but to get groceries you'd have to go physically to the store. To me, that was a broken experience. Two places, one was offline and one was online, that was always broken. I wanted to create something that could solve that problem. For me, it was very clear, I had the exact product I wanted to build and had the logistic experience. That cross-section was what put me in the position of building instacart.

Since then I've brought on two co-founders, both have been working on several startups. One was the first engineer at AngelList, a foundational knowledge of building networks. The other, on the other hand, has previously been a founder and CEO of a company that was acquired recently by Location Labs. He has a lot of operational experience. Right now the team is structured, I'm focused on the product and the logistics, Brandon is focused on the technology and Max is doing the operations.

BI: Why start with groceries?

AM: Everyone has to go grocery shopping, even if you don't cook you do need the basic cereals, your sundries, your toilet paper, your toiletries. Strategically speaking, we started with that like Amazon started with books. Amazon expanded to other categories, but when they started with books they were doing better than everyone. We wanted to laser-focus on groceries and do better than what everyone else did.

"Amazon expanded to other categories, but when they started with books they were doing better than everyone. We wanted to laser-focus on groceries and do better than what everyone else did."

We started with groceries because that's a problem that's not solved.

In the future, we'd like to add any unconsidered good as part of Instacart or if there are other apps we're building. We aren't going to get into the Apple Store, we're not gonna let you buy a big screen TV. We don't think we can add much value there, you don't need those things in an hour. You need something more impulsive or unconsidered.

BI: How do you handle the logistics?

AM: We use something called managed crowdsourcing. It's different from other platforms, managed crowdsourcing means when you order something on Instacart, we ensure there's crowdsourced labor to serve your requests. These are trained people who are equipped with an Instacart shopper app. This app is extremely intelligent, when they are at the store, we know exactly where all the items are located, what department, what isle, what shelf. The drivers are routed in the store as well as outside. We get as much efficiency as possible when we fulfill these requests. We charge $14.99 for one hour and $3.99 for three-hour deliveries. We're going to expand it to scheduled deliveries, for later today, for the next day. Our logistics are so efficient that we can give you that pricing.

BI: Do you guys see yourselves as being the go-to option for same-day deliveries?

AM: The scale is enormous, we've already delivered tens of thousands of items and we've only been operational for three weeks. There's this concept of a jewel on the Internet, where there's Amazon.com, that's where you go to shop. In the upcoming years, Instacart is the place you're going to go shopping for groceries. After that, it's going to expand to other areas as well. Anything same-day, anything instant is something Instacart will be able to provide. Amazon has done an amazing job being the sole-shopping experience provider. They're also going into the same-day space, but they'll never have all the inventory in the city for you, and we'll be able to do that. Our scope is much larger than what it seems right now. Right now we're just focused on being the best grocery delivery.